SMALL - Telemetry SMALL - Radio
Thread Tools
Old Oct 28, 2010, 11:48 AM
hidaven is online now
Find More Posts by hidaven
Registered User
United States, NJ, Roseland
Joined Apr 2009
2,234 Posts
Discussion
Wing incidence, declinage, dirty words....

OK, the dirty words came out after I found my new planes wings in a mess. I have an eflite Alpha 450. I had to adjust the tail a bit right as the tail and main wing were not level with each other.

Now to make matters worse, The plane is climbing even with the COG much forward than it should be! I almost have the elevator 15 clicks down just to level it.

So can this wing be off front to back? Im guessing that pitching the main wing forward will help with the absurd climbout, or maybe the tail?

I guess to start a description of declinage/ incidence is needed. I can barely spell them let alone define them...lol

Thanks in advance!
-dave
hidaven is online now Find More Posts by hidaven
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 28, 2010, 12:15 PM
CNY_Dave is offline
Find More Posts by CNY_Dave
DX5e fatal flaw- PM me!!!!
United States, NY, Cortland
Joined Sep 2010
2,840 Posts
Is it climbing with the body pretty level or with the body aligned with the climb?

Where is the CG supposed to be, and how much did you move it by?

Dave
CNY_Dave is offline Find More Posts by CNY_Dave
Reply With Quote
Old Oct 28, 2010, 12:25 PM
hidaven is online now
Find More Posts by hidaven
Registered User
United States, NJ, Roseland
Joined Apr 2009
2,234 Posts
plane climbs when level at about half stick. Im about 1/2 inch -3/4 inch forward of the rec. COG. If I take it up and do a 45 degree dive it pulls up quickly. This is with at least 12 clicks down of elevator. maybe theres helium in the tires??? lol. Either one or both of these wings must be angled up too much. Wonder how I'd know which one...or both? Confusing : (
hidaven is online now Find More Posts by hidaven
Reply With Quote
Old Oct 28, 2010, 12:53 PM
Tepid Pilot is offline
Find More Posts by Tepid Pilot
Built For Comfort
Tepid Pilot's Avatar
South Central Texas
Joined Aug 2009
884 Posts
You need to carefully check all your alignments and control surfaces. What, exactly, did you do to the tail to adjust it "level" to the wing? Did you mean level as viewed straight on from the front or the rear, or level as seen from a side view?

TP
Tepid Pilot is offline Find More Posts by Tepid Pilot
Reply With Quote
Old Oct 28, 2010, 12:54 PM
eflightray is offline
Find More Posts by eflightray
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
15,184 Posts
In the 'good old times', when trimming free flight models, that meant putting some packing under the wing trailing edge to reduce the incidence. (Tricky on some RC models). But we would also do it on very low power or for the glide. Then adjust the down thrust to reduce the climb on power.

Trimming for a glide is always worth doing first, with the CG in the recommended spot.
eflightray is offline Find More Posts by eflightray
Reply With Quote
Old Oct 28, 2010, 02:45 PM
hidaven is online now
Find More Posts by hidaven
Registered User
United States, NJ, Roseland
Joined Apr 2009
2,234 Posts
If you stood behind the plane, I adjusted the tail to slant a bit more to the right. Now I have both wings lined up left to right. i also put a 1/8 2 inch piece of flat wood (stir stick) under the moddle of the wing to tip it a little forward to reduce the angle of attack. Is that a good idea or should I have adjusted the tails angle of attack a bit forward instead? The plane always needs down elevator to keep it level, even in level flight. I needed to adjust the trim to the point where its notably down before I even take off. Just wants to climb and its not over powered.....Wing angle front to back must be off somehow....


Quote:
Originally Posted by Tepid Pilot View Post
You need to carefully check all your alignments and control surfaces. What, exactly, did you do to the tail to adjust it "level" to the wing? Did you mean level as viewed straight on from the front or the rear, or level as seen from a side view?

TP
hidaven is online now Find More Posts by hidaven
Reply With Quote
Old Oct 28, 2010, 02:59 PM
Tepid Pilot is offline
Find More Posts by Tepid Pilot
Built For Comfort
Tepid Pilot's Avatar
South Central Texas
Joined Aug 2009
884 Posts
Quote:
Originally Posted by hidaven View Post
If you stood behind the plane, I adjusted the tail to slant a bit more to the right. Now I have both wings lined up left to right. i also put a 1/8 2 inch piece of flat wood (stir stick) under the moddle of the wing to tip it a little forward to reduce the angle of attack. Is that a good idea or should I have adjusted the tails angle of attack a bit forward instead? The plane always needs down elevator to keep it level, even in level flight. I needed to adjust the trim to the point where its notably down before I even take off. Just wants to climb and its not over powered.....Wing angle front to back must be off somehow....
Raising the trailing edge of the wing, or the leading edge of the horizontal stabilizer will each have the same effect of reducing the wing's angle of attack relative to the horizontal stabilizer. I'm wondering if when you adjusted the tail to be properly aligned with the wing you may have inadvertently added some "up" trim. It might be worth your while to remove all of the shims and try flying the airplane even though the tail may not be perfectly lined up. Very hard to diagnose this correctly without actually seeing the airplane.

TP
Tepid Pilot is offline Find More Posts by Tepid Pilot
Reply With Quote
Old Oct 28, 2010, 05:17 PM
hidaven is online now
Find More Posts by hidaven
Registered User
United States, NJ, Roseland
Joined Apr 2009
2,234 Posts
Should the incidence be the same for the hoizontal stabilizer and the main wing?
hidaven is online now Find More Posts by hidaven
Reply With Quote
Old Oct 28, 2010, 05:40 PM
Sparky Paul is offline
Find More Posts by Sparky Paul
Ascended Master
Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
13,621 Posts
First, which airplane is it?
Sparky Paul is offline Find More Posts by Sparky Paul
Reply With Quote
Old Oct 28, 2010, 05:54 PM
mocgp is offline
Find More Posts by mocgp
Registered User
Greenville, SC
Joined Jul 2007
79 Posts
Dave: the dirtiest word you used was "declinage." Sorry, not in anyone's dictionary. Quite sure you meant decalage.
mocgp is offline Find More Posts by mocgp
Reply With Quote
Old Oct 28, 2010, 06:29 PM
Tepid Pilot is offline
Find More Posts by Tepid Pilot
Built For Comfort
Tepid Pilot's Avatar
South Central Texas
Joined Aug 2009
884 Posts
Quote:
Originally Posted by hidaven View Post
Should the incidence be the same for the hoizontal stabilizer and the main wing?
Possibly, but unless it says in the manual, this question is best addressed to E-Flite tech support. Normally this information is on the plan side view, but since the Alpha 450 is an ARF-type airplane...

TP
Tepid Pilot is offline Find More Posts by Tepid Pilot
Reply With Quote
Old Oct 28, 2010, 08:58 PM
bobw53 is offline
Find More Posts by bobw53
Registered User
USA, NM, Hatch
Joined Sep 2010
45 Posts
Not meaning to hijack the thread, but..... I think this is the same.

I have a plane that flies like (pick expletive, it fits them all). climbs, climbs, climbs, climbs, climbs. If its not falling, its climbing. Tons and tons of down elevator to get it to fly straight, and still climbs like crazy with throttle, like a retarded turtle, just wants to roll over on its back.

Read this thread this morning and threw an angle gage on her today. Granted the wing is curved a bit on the bottom, but it averages out to the wing being inclined about 3 degrees (quick and dirty measurements, easily seen by eye) to the horizontal stabilizer.

Went to the other plane I have and the horizontal stabalizer is level within maybe 1/2 a degree of the wing, and she flies nice (if I can get it in the air). Trims out with a level elevator.

So a few questions.

What should the angle be between the wing and horizontal stabilizer be? I'm guessing it has to do with CG. MD80's at the airport with the engines in the ass end seem to have the horizontal stabilizer pointed into the ground.

On this POS plane I've got, a Megatech Ambassador (free on credit card points, so I have an excuse), coming out of a turn, it always gains altitude, bad angles?

This thing is twitchy, hard as heck to maintain a level altitude, the CG is where I think it should be, about 1/3 of the way back on the wing. I even added some nose weight to it, but all it wants to do is climb.

I've already decided to gut it and shelve it, and have a GWS e-starter on the way. However with what I've read here, I'm going to shim the wing up, get it level with the HS and see how she does this weekend. I hope it still flies like crap so I still have a good excuse for blowing some more money.
bobw53 is offline Find More Posts by bobw53
Reply With Quote
Old Oct 29, 2010, 07:18 AM
CNY_Dave is offline
Find More Posts by CNY_Dave
DX5e fatal flaw- PM me!!!!
United States, NY, Cortland
Joined Sep 2010
2,840 Posts
If nothing else, you are creating a lot of drag if wing and Hstab incidence are different.

My guess would be they should be the same for stability, if the Hstab and wing don't match and it flies level, the Hstab is going to be compensating for a funky CG.

Dave
CNY_Dave is offline Find More Posts by CNY_Dave
Reply With Quote
Old Oct 29, 2010, 07:45 AM
flypaper 2 is online now
Find More Posts by flypaper 2
Canadian Bacon
flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
14,468 Posts
Just to clarify, decalage is the angular DIFFERENCE between the wing and stabilizer. Doesn't really matter where they're mounted on the fuse. 3 degrees positive decalage means the wing would be plus 3 degrees relative to the stabs 0 degrees.
So to start from scratch, stick a pin in the centre, most forward point on the curved leading edge of the wing. Stick another pin in the trailing edge of the wing. Now put the elev. at neutral and stick a pin in the leading and trailing edge. Prop it up on your workbench so the pins on the wing measure the same from the bench to the pins, say 3 ins. Now measure the stab pins from the bench and adjust the stab so the measurement from the bench is the same front and back. Say 2 in. at the front and 2 1/8 at the back, then lower the back down to 2 ins.
If the wing is rubber banded on, set the stab to 0/0 on the bench, then shim the wing so the wing leading edge and trailing edge measure the same from the bench. This is the starting point. Then we need to set CG and motor thrustline.

Gord.
flypaper 2 is online now Find More Posts by flypaper 2
Reply With Quote
Old Oct 29, 2010, 10:43 AM
ChillPhatCat is online now
Find More Posts by ChillPhatCat
Fueled by Arabica Beans
ChillPhatCat's Avatar
United States, NY, Syracuse
Joined Oct 2008
4,488 Posts
Quote:
Originally Posted by bobw53 View Post
Not meaning to hijack the thread, but..... I think this is the same.

I have a plane that flies like (pick expletive, it fits them all). climbs, climbs, climbs, climbs, climbs. If its not falling, its climbing. Tons and tons of down elevator to get it to fly straight, and still climbs like crazy with throttle, like a retarded turtle, just wants to roll over on its back.

Read this thread this morning and threw an angle gage on her today. Granted the wing is curved a bit on the bottom, but it averages out to the wing being inclined about 3 degrees (quick and dirty measurements, easily seen by eye) to the horizontal stabilizer.

Went to the other plane I have and the horizontal stabalizer is level within maybe 1/2 a degree of the wing, and she flies nice (if I can get it in the air). Trims out with a level elevator.

So a few questions.

What should the angle be between the wing and horizontal stabilizer be? I'm guessing it has to do with CG. MD80's at the airport with the engines in the ass end seem to have the horizontal stabilizer pointed into the ground.

On this POS plane I've got, a Megatech Ambassador (free on credit card points, so I have an excuse), coming out of a turn, it always gains altitude, bad angles?

This thing is twitchy, hard as heck to maintain a level altitude, the CG is where I think it should be, about 1/3 of the way back on the wing. I even added some nose weight to it, but all it wants to do is climb.

I've already decided to gut it and shelve it, and have a GWS e-starter on the way. However with what I've read here, I'm going to shim the wing up, get it level with the HS and see how she does this weekend. I hope it still flies like crap so I still have a good excuse for blowing some more money.
CG at 1/3 of the chord from the leading edge is asking for trouble with anything short of a 3D plane. It should be more like 1/4 of the chord. Sounds like it behaves exactly like a tailheavy plane.
ChillPhatCat is online now Find More Posts by ChillPhatCat
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Ezytwin- wing incidence Camm The Builders Workshop 9 Oct 29, 2010 12:28 PM
Discussion Wing Incidence vs Float Incidence sneasle Waterplanes 8 Jun 08, 2010 12:09 PM
Discussion Whats the best way to check wing incidence or motor incidence? marcwv 3D Flying 0 Feb 04, 2007 11:31 PM
Question Motor, wing and stab alignment - all parallel for 3D? Wing to stab incidence? CactusJackSlade 3D Flying 4 Jan 21, 2004 11:19 AM
Wing Incidence vs Horizontal Stab Incidence kelvin Power Systems 1 Mar 06, 2002 08:49 AM